The present invention relates to a method of and a system for controlling fuel feeding aggregates in motor vehicles, as well as to a vehicle provided therewith and having two or more electrical fuel feeding aggregates.
German patent document DE 195 04 217 A1 discloses a device for feeding fuel from the supply tank to an internal combustion engine of a motor vehicle. The device has a container arranged in a supply tank, from which a feeding aggregate aspirates the fuel and feeds it to the internal combustion engine. A fuel conduit branches from the pressure side of the feeding aggregate. It opens into a supply tank and is connected to a suction jet pump. The suction jet pump feeds fuel from the supply tank into the container. A throttle is arranged in the fuel conduit upstream of the suction jet pump. As a result, the fuel which exits from the suction jet pump has a lower pressure than at the pressure side of the feeding aggregate. Thereby the fuel which flows from the suction jet pump in heated condition has less tendency for evaporation and the operation of the suction jet pump is improved.
When in the modern constructions two or more electrical fuel pumps are arranged in a supply tank, they are can be controlled simultaneously or in other words controlled electrically parallel to one another. Thereby it is guaranteed that in each inclined position of the motor vehicle, the fuel supply is provided. This however has a disadvantage that as a result a high electrical power consumption of the electric fuel pumps takes place, and the high fuel return flow in the tank causes heating of the tank. With the parallel control of all fuel pumps, disturbing flow noise and pump noise can be generated.
Individual electrical fuel pumps which are incorporated in an electrical, parallel-operating control can not be easily diagnosed. A dry running of a single electrical fuel pump can not be reliably prevented, since with the parallel electrical control, all fuel feeding aggregates are controlled simultaneously.
Accordingly, it is an object of present invention to provide a method of and a system for controlling fuel feeding aggregates in motor vehicles as well as a motor vehicle provided therewith which avoids the disadvantages of the prior art.
In accordance with the inventive method, in dependence on the data determined by a control unit about longitudinal and/or transverse angles of the motor vehicle, such fuel feeding aggregates are controlled which guarantee an efficient aspiration of fuel.
In all-wheel vehicles, for example military vehicles, the available inclination angle information can be evaluated through a longitudinal and a transverse inclination angles of the vehicles. In dependence on the determined inclination angle of the motor vehicle on the ground with consideration of the mounting position of the electrical fuel pump, only that fuel pump is controlled which guarantees an efficient aspiration of fuel even with a low tank filling level. The control of the fuel feeding aggregates in dependence on the inclination angle information of the motor vehicle reduces the electrical power consumption significantly, since only that feeding aggregate is controlled which guarantees a reliable fuel supply. A fuel return and heating of the tank connected therewith in the inventive control method is substantially lower. Furthermore, the generated flow noise and the pump noise which can occur during operation of the fuel feeding aggregate is reduced to an unchanged minimum.
It is also another feature of present invention to provide a vehicle with the above mentioned control system and method.
In the inventive fuel supply system the control unit is formed so that, depending on the data of the longitudinal and/or transverse inclination of the vehicle, it controls such fuel feeding aggregates that guarantee an efficient aspiration of fuel.
In accordance with a preferable embodiment of the present invention, the switching of the fuel feeding to a fuel feeding aggregate is performed after elapsing of a preselected time period. Thereby during a transition time period the fuel supply is guaranteed. It involves an additional electrical power consumption, however only for a limited time. Preferably the switching of one or several fuel feeding aggregates is performed when a threshold value for the longitudinal or side inclination of the vehicle chassis is detected for a longer time period. In the event of short inclination change, a switching between various fuel feeding aggregates can be avoided. Depending on the terrain configuration at which the vehicle has to deal, the threshold for the vehicle inclination in longitudinal or transverse direction, whose exceeding causes the desired control of a fuel feeding aggregate, can be provided individually and adjusted independently from one another.
In accordance with a preferable embodiment of the inventive method, a switching over condition for a first fuel feeding aggregate can be determined so that for positive angle xcex2 which is greater than a threshold k1 a switching off of the first feeding aggregate is performed. This condition must be fulfilled for a first time period t1, until the switching off of the first fuel feeding aggregate is performed. On the other hand, a switching of the first fuel feeding aggregate to a fuel feeding aggregate maintaining the fuel supply can be performed when the corresponding detected positive angle xcex2 is less than the threshold value k2. The threshold value k2 is selected smaller than k1 whereby a hysteresis condition can be produced, to exclude switching on and off between the fuel feeding aggregates during passage of a terrain portion under the angle xcex2
When with the angle variables xcex2 the inclinations of a motor vehicle around a transverse action in clockwise direction are identifiable, then the method is expanded in advantageous manner by detection of the angle a occurring opposite to the clockwise direction around the transverse axis. Analogously, the detected negative angles xcex1 which are greater than a predeterminable threshold value k1 can be used as a switching condition for the switching off of a further fuel feeding aggregate. This angle a also can occur for a time period t2, until the switching off of the further feeding aggregate is performed. When the continuously occurring angle xcex1 is located under the threshold k2 then a new switching of a fuel feeding aggregate for taking over the fuel supply is performed. For the threshold value it is true that the threshold value k2 is less than the threshold value k1.
With modern vehicle electronic systems, vehicle computers, navigation devices or the like, the data for vehicle inclination about transverse and/or longitudinal axis, can be determined in cycles and continuously supplied to the control unit.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.